Quality of Life in Adult Patients with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia Treated with Obecabtagene Autoleucel (obe-cel) in the Pivotal Phase 2 Felix Study

Introduction The FELIX study (NCT04404660) is an ongoing, open-label, single-arm, Phase 1b/2 clinical trial evaluating the safety and efficacy of obe-cel, a chimeric antigen receptor (CAR) T-cell therapy for adults with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL). Objectives A secondary study objective was to evaluate changes over time in responders in patient-reported outcome measures (PROMs) assessing symptoms, functioning, and overall quality of life (QoL) using the EuroQol-five-dimensions-5 levels questionnaire (EQ-5D-5L) visual analogue scale (VAS) and symptom, functioning, and Global Health Status (GHS) scores from the European Organisation for Research and Treatment of Cancer Quality of Life questionnaire – Core 30 (EORTC QLQ-C30). This abstract describes results specifically for the EQ-5D-5L VAS and EORTC QLQ-C30 GHS scores in patients receiving obe-cel. Methods Obe-cel was administered on Days 1 and 10; the end of the treatment phase was defined as 1 month post-first infusion. PROMs data were collected at baseline and Day 28 (i.e., the treatment period and first assessment) and at Months 3, 6, 9, and 12 (i.e., the efficacy and safety follow-up period). Change in PROM scores were assessed descriptively by analyzing mean changes from baseline for the EQ-5D-5L VAS and EORTC QLQ-C30 GHS. Both PROMs are scaled with scores ranging from 0–100, with higher scores indicating higher QoL. Trajectory plots displaying mean change from baseline and 95% CIs were plotted through Month 12. Changes from baseline were interpreted using pre-specified thresholds defining improvement or deterioration, with a ≥10-point increase or decrease used to distinguish meaningful improvement or deterioration, respectively. Results A total of 94 patients in Cohort IIA received an infusion of obe-cel. Of these, responding patients reported VAS (n=70) and GHS (n=71) data at baseline (May 2023 data cut-off). PROMs data were not collected after treatment failure or relapse. The longitudinal trajectory of patients’ VAS scores showed an expected reduction in average measured QoL at Day 28, but not to a level indicating meaningful deterioration (Fig 1). Starting at Month 3, and in all subsequent months, average scores exceeded baseline scores to levels indicative of meaningful improvement and remained at that level throughout the 12 months. Maximum improvement in scores occurred in Month 6. For the GHS scores, the overall pattern of results was similar (Fig 2). Conclusion After an initial deterioration post-infusion, patients recovered to and later exceeded baseline status in overall QoL. EORTC QLQ-C30 scores provide QoL data that are not routinely collected in CAR T trials for ALL. These data demonstrate that obe-cel therapy is associated with a meaningful improvement in QoL by 3 months post-infusion and provide a basis for further analysis as additional FELIX trial data become available.